The advent of self-developing collapsible cameras has introduced a new dimension in rapid on-the-scene film developing.
The new type Polaroid SX-70 camera develops brilliantly colored photographs external to the camera in a process that compares, for example, to time lapse photography in its ability to rapidly and somewhat mysteriously bring color photographs to life.
The SX-70 camera utilizes a new film composition and chemistry different from ordinary self-developing cameras. The use of a special film therefore allows the film package to contain a battery within the film pack. This battery provides power both for the camera operation mechanism and for energizing flash lamps when flash lamps are necessary.
So far the new SX-70 camera has been mainly limited to an explosion type flash bulb of the type using consumable metal powders heated to irridescense in an oxygen rich environment. Several of these flash bulbs have been combined in a series to form a flash pack or bar in order to provide a sufficient number of flashes roughly equivalent to the useful life of the battery contained within the film package. One example of such a flash bar device is disclosed within U.S. Pat. No. 3,748,985 assigned to the Polaroid Corporation.
The use of a number of explosive flash bulbs has presented a problem in view of the very nature of its expendibility since the flash bulbs have to be disposed of when used.
The Polaroid SX-70 type camera by the use of unique self-developing films avoids a lot of the messy paper containers and chemicals necessarily involved in earlier type self-developing films. The new film process presents an ecological advancement since less material remains to be discarded or disposed of than by methods previously employed. The use of disposable flash bulbs, consisting mainly of glass and plastic, therefore presents a problem of disposal inconsistent with the ecological advantages presented with the advent of the SX-70 camera.
The use of a large number of disposable flash bulbs within a package results in an uneven distribution of light, and in cases where the subject is mainly illuminated by the flash, for example, in low ambient light area, "hot spot" regions of intense illumination can occur due to the particular narrow reflector geometry. Another limitation which sometimes occurs when the lighting ambient level is quite low, and when the principle source of illumination is mainly provided by the flash bulb, is the possibility of a slightly blurred photographic image when the subject being photographed is in motion.
All of the above disadvantages can be overcome by the use of electronic flash lamps of the type employing a xenon arc tube. The tube has very long operating life and presents no immediate ecological disadvantages. The optimum reflector geometry provides a uniform light distribution pattern for eliminating "hot spots" and, due to its very short and intense flash duration, is able to take action pictures in low lighting ambients without blurring. Heretofore, electronic flash lamps have not generally been utilized for self-developing compact type collapsible cameras mainly because the flash assembly apparatus and related electronic circuitry was not compatible with the camera's compact design features. The electronic flash attachments of the prior art were very effective for providing sufficiently bright and concentrated light for photographic requirements, but required auxiliary power-packs that could not be conveniently and readily removed from the camera prior to collapsing. The collapsible feature of the camera afforded easy storage and handling facility which was not in accordance with the removal of auxiliary and in some cases, bulky electronic flash gear.
The purpose of this invention is therefore to provide an improved flash attachment readily and conveniently removable from collapsible self-developing cameras. The attachment multi-functionally utilizes part of the film power-pack voltage in cooperation with an auxiliary battery voltage to provide thousands of high intensity flashes of extremely short pulse duration.